1. Field of the Invention
The present invention relates generally to security systems and, more specifically, to security systems for electronic circuits.
2. Related Art
Point of sale (POS) terminals allow customers to make payments using a variety of payment instruments such as credit cards, debit cards, smart cards, ATM cards, etc. To ensure that the payment information transmitted from the POS terminals to a payment center is not intercepted, this information is typically encrypted and secured through other means (e.g., digital authentication) during transmissions.
However, confidential payment information entered by the user into the POS terminal could still be intercepted by tampering with the POS terminal. To curb such interception and any tampering of the keypad and processor, processors and other circuitry in the POS terminal are typically embedded in material such as epoxy resin which is potted to the keypad, thereby integrating the keypad and the circuits into a single module.
A cross-section of a typical prior art potted POS terminal 100 is shown in FIG. 1. Potted POS terminal 100 includes a top case 110, a bottom case 120, keys 130 and security components 140. The circuitry within POS terminal 100 is enclosed within a PCB 160 and potted in an epoxy compound 150. Security components 140 are connected to and detect any interruption in PCB 160. In an attempt to drill through PCB 160, the PCB circuit would be interrupted and a detection circuit would trigger a security response (e.g. erasing any confidential information stored in the circuitry of POS terminal 100).
While these security measures are sufficient to deter some tamperers, they could still be circumvented (e.g. by opening the POS terminals and using appropriate chemical substances to remove the potting material).
In addition, epoxy potting is expensive and prevents both authorized and unauthorized access to the circuitry within the POS terminal. For example, once a circuit is potted it can no longer be accessed for repair and maintenance purposes. This has the undesirable effect of increasing repair and replacement costs and, at least potentially, of reducing manufacturing yields. Furthermore, the epoxy potting process is both lengthy and generates fumes that must be removed by a special ventilation system.
As a result, there is a need for a less expensive, more secure technique for preventing unauthorized access to the circuitry within a POS terminal.